The present invention relates to mark verification systems and more specifically to a mark verification system that uses versatile methods that enable various verification configurations to be employed.
Many different industries require that marks be applied to manufactured components so that the components can be tracked during distribution, when installed or assembled, during maintenance processes, during use and after use. For instance, in the jet engine industry, jet engines include, among other components, turbines that include turbine blades that are manufactured in various size lots. Here, each turbine blade is marked when manufactured so that the blade can be tracked. Prior to the blade being disposed of, if any defect is ever detected in the blade, the defect can be traced back to a lot and a manufacturing process associated therewith so that any possible defects in other blades of the lot can be identified. Where marks are applied directly to components/parts, the marks are generally referred to as direct part marks (DPMs).
To directly mark components, known marking systems have been set up that include a marking station that applies a mark to a component. For instance, in at least some cases a marking station will apply a DataMatrix barcode symbol to each manufactured component where a DataMatrix symbol is a two-dimensional barcode that stores from 1 to about 2,000 characters. An exemplary DataMatrix symbol is typically square and can range from 0.001 inch per side up to 14 inches per side. As an example of density, 500 numeric only characters can be encoded in a 1-inch square DataMatrix symbol using a 24-pin dot matrix marking machine.
Despite attempts to apply marks that can be read consistently thereafter, sometimes mark application errors occur such that the mark cannot be subsequently consistently read and decoded properly. For instance, in some cases the surface to which the mark is applied may be somewhat discolored so that the contrast of the mark to the background of the application surface is not optimal. As another instance, in some cases where a mark consists of a plurality of dots, the dot sizes may be too large so that spaces there between are not perfectly discernible or the dot sizes may be too small to be recognized by some types of readers. As still other instances, axial non-uniformity of grid non-uniformity of the applied mark may be too great to reliably read. Many other mark metrics may be imperfect and may render mark difficult if not impossible to decode using many readers.
Whether or not a mark that has been applied to a component is readable often depends on the reading and decoding capabilities of a reader used to read and decode the mark. For instance, some relatively complex and expensive readers are capable of reading extremely distorted marks while cannot read marks that are not almost perfect.
To verify that applied marks are of sufficient quality to be read by readers at a specific facility (i.e., by the least sophisticated reader that is used at a specific facility), often marking systems will include, in addition to a marking station, a stationary verification station and at least a portion of a transfer line to transfer freshly marked components from the marking station to the verification station. Here, after a mark is applied to a component, the component is transferred via the transfer line to the verification station where the mark is precisely aligned with an ideal stationary light source and a stationary camera/mark reader that is juxtaposed such that a camera field of view is precisely aligned with the mark. After alignment, the reader reads the mark and attempts to verify code quality.
Verification can include several steps including decoding the mark and comparing the decoded information to known correct information associated with the mark that should have been applied. In addition, verification may also include detecting mark size, geometric mark characteristics (e.g., squareness of the mark), symbol contrast, quantity of applied ink, axial non-uniformity, grid non-uniformity, extreme reflectance, dot diameter, dot ovality, dot position, background uniformity, etc.
When a mark does not pass a verification process (i.e., mark quality is low), the marked component may be scrapped to ensure that the marked component does not enter distribution channels.
When a marked component passes a verification test at a manufacturing facility and is shipped to a client facility, when the component is received at a client's facility, it is often desirable for the client to independently verify that mark quality is sufficient for use with all of the readers at the facility and to decode the mark information to verify component type, to establish a record of received components, to begin a warranty period, etc. To this end, some known facilities include stationary verification systems akin to the verification stations at the component manufacturing facility described above that perform various verification processes including decoding to verify mark quality. To this end, known verification systems, like the known verification station described above, include some stationary mechanism (e.g., mechanical locking devices, sensors, etc.) for precisely aligning the mark on the component with a stationary ideal light source and a stationary camera so that the camera can generate an image of the mark and a processor can then glean mark verifying information from the mark.
While marking/verification systems of the above kind work well to mark components and to verify mark quality, such systems have several shortcomings. First, a full blown mark verification station that requires specific lighting, mark and component juxtaposition and reader alignment requires a large amount of hardware dedicated to each verification process. In the case of a verification station that follows a marking station, the additional hardware includes an extra transfer line station, a dedicated light source, alignment sensors, etc. In the case of a verification system at a client's facility the additional hardware includes a dedicated camera, light source and component alignment mechanism. Additional hardware increases costs appreciably.
Second, stationary verification stations and systems slow down the manufacturing and component use processes as additional component movements and alignment procedures are required at both the manufacturing facility and a client's facility. In addition to requiring more time, additional process steps reduce product throughput and therefore should be avoided whenever possible.